1. Field of the Invention
This invention relates generally to mechanical locks for holding overlapping flaps of a wrap-around carton in place. More particularly, it is a primary lock system and a secondary “backup” locking system.
2. Prior Art
When fabricating a carton from a paperboard blank, opposite ends of the blank are conventionally attached to each other by glue or by a mechanical lock to form the bottom panel of the carton. In the case of a wrap-around carton, flaps located on the ends of the blank typically are overlapped and engaged with one another by mechanical locks formed in the flaps to form the bottom panel of the carton. Since the bottom panel must maintain its integrity throughout the use of the carton, it is essential that the locking system be capable of supporting the weight of the packaged articles, and remain engaged during shipping and handling of the constructed carton.
One approach to provide a stable mechanical lock assembly utilizes both primary and secondary locks. An example of such locking system is disclosed in U.S. Pat. No. 5,443,203 to Sutherland.